There are a large number of car washing installations which utilize highly automated and expensive washing and drying machinery. However, there are also a large number of do-it-yourself or one-man-operated car washing installations which of necessity require simpler, less expensive car washing equipment. Many of such car washing installations utilize a relatively simple apparatus in which water flows through an overhead swivel cartridge to a car washing hose which is supported by a boom assembly attached to the rotatable outlet of the swivel cartridge so that the hose can be swung about 360.degree. and the entire car can be washed without needing to pull the hose over or under the car. Such apparatus is not only inexpensive and efficient but also very dependable. However, on occasion, the swivel cartridge wears out and it must be replaced. Unfortunately, the replacement of the swivel cartridge normally requires practically a complete disassembly of the entire apparatus thus resulting in considerable downtime. There is a need, therefore, for a car washing apparatus of the type employing an overhead swivel cartridge in which the swivel cartridge can be easily and quickly replaced when needed.